Low-Pressure Metallo-Organic Chemical Vapor Deposition of Ga_xIn_1−xAs_yP_1−y Alloys

This chapter discusses that metallo-organic chemical vapor deposition (MOCVD) has emerged as a valuable tool for the growth of device-quality epitaxial layers of InP, G_0.47In_0.53 As, and Ga_xIn_1–xAs_yP_1–y. The GaInAsP/InP alloy system has many advantages and has been given considerable research attention for electro-optical device applications. However, there are still important unsolved problems for the growth of these materials with liquid-phase epitaxy (LPE), vapor-phase epitaxy (VPE), and molecular-beam epitaxy (MBE). One of these is the development of practical LPE techniques for reproducibly growing InP and GaInAsP alloys with a low carrier concentration level. This is especially important for the fabrication of p-i-n and avalanche photodiodes. A further problem with LPE is the growth of InP on longer-wavelength layers, such as GaInAs, without any interface compositional grading layers and anti-melt-back layers. With the VPE technique, it is difficult to obtain misfit dislocation-free InP-GaInAsP-InP heterostructures and very thin layers. A problem for the MBE technique is the growth of phosphorus-bearing alloys.